Core drier clamping mechanism



March 14, 1967 EGAN ETAL 3,308,512

CORE DRIER CLAMPING MECHANISM Filed June 3, 1965 2 Sheets-Sheet '1 47 [6* Ax a if r2! w m m T A I I v v U v v U w v v; UV A, QVUQI, ,vuc

7? w '7? f ii INVENTORS l 6e 0/0 #6 Z y R0555 March 14, 1967 5, EGAN ETAL CORE DRIER GLAMPING MECHANISM 2 Sheets-Sheet 2 Filed June 3, 1965 an e 0272205022 @21 ATRIVEY United States Patent CORE DRIER CLAMPING MECHANISM Gerald H. Egan, Beamsville, Ontario, and Ross C. Smith and Stanley M. Thompson, St. Catharines, Ontario,

Canada, assignors to General Motors Corporation,

Detroit, Mich, a corporation of Delaware Filed June 3, 1965, Ser. No. 461,038 Claims. (Cl. 2213) This invention relates to core blowing apparatus and more particularly to a core drier clamping mechanism for use with automatic core blowers.

It is well known in foundry art that mass production of foundry cores is usually accomplished by forming the core material to the desired shape in a metal core box. The cores are made from a mixture comprising sand and a binding agent. To fill the core box rapidly a technique called core blowing is used wherein core materials suspended in a stream of air enter the cavity at high ve- 4 locity through blow holes. The core material is trapped in the core box while the air is allowed to escape to the atmosphere.

An automatic core blower is a machine which performs the above operations. For the purpose of illustrating the function and utility of the subject clamping mechanism it would be helpful to briefly summarize the operation of a typical core blowing machine.

In general, this machine consists of the lower half of a core box slidably mounted on a table. The upper half of the core box attached to a sand hopper is mounted for vertical movement above the lower core box. During the blowing operation the upper core box is first lowered over the lower core box and a core is blown. Thereafter the upper core box is raised and the lower core box is mechanically moved onto a roll-over table. The core drier is then placed manually over the exposed upper part of the core and clamped to the core box.

The usual method of holding the core drier on the core box is by an air cylinder operated clamp arm which is permanently attached to the body of the roll-over table. The clamp arm holds the drier against the core box. The drier is placed on the core box located by the core box pins, the operator has to lift the drier up and over the clamp arm and lower the drier onto the core guided by the pins.

The roll-over table is rotated 180 whereby the core is now supported by the core drier which is still clamped to the core box. The arm type clamp is then removed from the drier whereby the drier and core may be removed from the lower core box. The drier containing the core is then placed in an oven and dried.

The core drier clamping mechanism of this invention is a means for holding the core drier onto the lower core box half during the roll-over operation and is intended to replace the air cylinder operated clamp arm mech anism. In the preferred embodiment the clamping mechanism of the invention also functions as a guide for the positioning of the upper core box half against the lower core box half and subsequently for the positioning of the core drier over the core and the lower core box half.

Thus, it is an object of this invention to relieve the fatigue of the operator caused by having to lift the drier so far and to provide a simpler and more efficient means for holding the drier to the core box.

It is a further object to provide a device which will serve both as a guide pin for the upper core box half and the core drier and as a clamping mechanism for the core drier on the roll-over operation.

It is a still further object of this invention to provide a reciprocally operative holding pin, which is piston actuated, for clamping the core drier to the lower core box half on the roll-over operation.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein the preferred embodiment of the present invention is clearly shown.

FIGURE 1 is a schematic drawing showing the upper core box half against the lower core box half in the core blowing position.

FIGURE 2 is a schematic drawing showing the upper core box half in the raised position and the lowerscore box half removed to the roll-over table. The core drier lhas been placed over the core and the lower core box alf.

FIGURE 3 is a schematic drawing showing the lower igre box half after the roll-over table has been rotated FIGURE 4 is a schematic drawing showing the core grit? and core after removal from the lower core box FIGURE 5 is a sectional side elevation view of the subject core drier clamping mechanism including a portion of a core dn'er and the lower half of a core box.

FIGURES 1-4 showing portions of the core blowing apparatus together with the following discussion will clearly illustrate the function and utility of the subject clamping mechanism at various stages of the core blowing process.

In FIGURE 1 is represented the upper core box half 10 and the lower core box half 12 in a core blowing position. The upper half of the core box 10 is attached to a sand hopper 14 and is mounted with means (not shown) for vertical movement. At this stage the pin 16 of this invention serves as a guide pin to assist in the proper positioning of the upper core box half 10. The core is blown with the sand-binder mixture entering through a blow hole 18. Then the upper core box half 10 is raised until it is clear of the lower core box half and the uncured sand core. The lower half of the core box 12 is supported on a table 20 with rollers 22 which can act as a horizontal conveyor. Adjacent to this table, but distinct from it is a roll-over table 24 mounted on an axle shaft 26 and in alignment with table 20. Table 24 also has rollers 28 or other suitable means for easily conveying the lower core box 12.

As soon as the upper core box half 10 is out of the way the lower core box half 12 may be moved onto the roll-over table 24, in the position shown in FIGURE 2. This move is effected by a hydraulic or air actuated arm (not shown), or by any other suitable means. A core drier 30 is then placed manually over the exposed upper part of the core 32, the pin 16 again acting as a guide pin, and is clamped to the lower core box half 12 by the pin 16. The details of the pin, as shown in FIGURE 5, and its operation as a core drier clamping mechanism will be fully discussed below. However, FIGURE 2 does show the bulge in the rubber sleeve 34 of the pin 16 which in accordance with this invention holds the core drier 30 to the lower core box 12.

At this point the roll-over table 24 is rotated on its axle shaft 26 by hydraulic or other means as shown in FIGURE 3. The lower core box half 12 is held to the table 24 by guide bars (not shown), or other suitable means, and the core drier 30 is held to the core box 12 by the clamping mechanism 16. The clamp L16 now releases the drier 30 whereby the core 32 is removed from the lower core box half 12. The drier 30 containing the core 32 as shown in FIGURE 4 is then placed in an oven and dried.

It is to be understood that the purpose of describing the apparatus as shown in the four figures of schematic drawings is intended to illustrate the invention and its utility. It will also be understood that the invention is useful in connection with other apparatus.

A s 'shown in FIGURE 5 the clamping device of this invention is associated with the lower core box and the core drier, and includes a pin 40, a bushing 37, a rubber sleeve 34, and means, which will be more fully discussed later, by which the pin may be moved through an axial stroke.

The pin 40 includes a cylindrical shaft portion 42 and a cylindrical head portion 41 of larger diameter. This shaft 42 is disposed perpendicularly to a flange or lug 70 extending from the top surface of the lower core box half and it passes through a hole 71 in the lug. As shown in FIGURE 5 the shaft 42 also extends above the core box lug 70 a distance greater than the thickness of the core drier lug 30. This shaft 42 terminates at its upper end in the enlarged head portion 41.

The enlarged head portion 41 has a flat lower shoulder 43 and a tapered upper shoulder 45. The upper shoulder is tapered to facilitate positioning of the upper core box half and the core drier.

Where the shaft of the pin passes through the core drier lug 70 it passes through a bushing 37 which acts as.a bearing for the shaft. As shown the bushing has a smaller lower diameter 36 which is adapted as to be firmly secured in the upper portion of the core drier lug 70 as for example by a press fit. The portion of the bushing 38 above the core box lug is of slightly larger diameter. It approximates the diameter of the enlarged head portion 41 of the pin. The inside diameter of the bushing 37 is, of course, approximately the same as the diameter of the pin shaft 42.

Situated about the shaft 42 of the pin 40 and between the shoulder 43 of the pin head 41 and the upper flat surface of the bushing 37 is a cylindrical rubber sleeve 34. It preferably has flat upper and lower radial surfaces and its outside diameter is approximately the size of the pin head 41 and of the larger portion of the bushing 38. The rubber sleeve 34 is of sufiicient length to extend from the upper surface of the bushing above the top surface of the core drier lug 30. The core drier lug has a hole 72 in it which will permit it to just fit over the pin head 41, rubber sleeve 34 and bushing 37.

It is apparent that when the pin is moved downwardly so that the pin head 41 compresses the rubber sleeve 34 against the upper surface of the bushing 37 the rubber sleeve 34 will expand outwardly against the surface of the hole 72 in the core drier lug and that portion of the sleeve above the core drier lug will bulge outwardly over the upper surface of the lug as shown by the dotted line eifectively clamping it to the lower core box half.

As shown in FIGURE 5 in the preferred embodiment of this invention the means for moving the pin through a short axial stroke comprises a cylinder 60 and a pneumatically or hydraulically actuated piston 47 reciprocally operable within the cylinder 60. The piston 47 is comprised of a piston head 48 secured to a piston rod 44.

The lower end of the pin shaft 42 is connected to a piston rod 44 and is secured thereto by a lock nut 46. The piston rod 44 is connected to a piston head 48 which also is secured by a lock nut 50. Included around the piston rod are a cylindrical cup or diaphragm 52, a spacer ring 54, and a bushing 56 carrying the O-rings 58 to provide a seal between the bushing 56 and the rod 44. The bushing 56 is firmly attached to the upper portion of a short stroke cylinder 60 as for example by screw threads. The cylinder head 62 is attached to the lower core box half 12 and is adapted to include a compression coil spring 64 which forces the piston 44 and piston rod 48 and the pin 40 up tending to relieve any pressure on the rubber sleeve 34. A hole 66 is drilled and tapped into cylinder 60 to receive a fitting (not shown) whereby fluid pressure may be admitted to the cylinder 60. A small hole 68 passes the fluid to the inside of the cylinder so that it may act upon the diaphragm'52 and force down the piston 47.

It can readily be visualized that when fluid pressure is admitted to the cylinder 60 the piston 47 will be forced downward against the spring 64. Thus the whole pin 40 is moved down. The rubber sleeve 34 is compressed between the head of the pin 41 and the stationary bushing 37. That portion of the sleeve 34 above the core drier lug section 30 is free to bulge outwardly as shown in FIGURES 2 and 3 whereby the drier is clamped securely to the core box .12.

When the fluid pressure is released by means external to the cylinder the coil spring 64 pushes up the piston 47 and thus the pin 40. The rubber sleeve 34 assumes its normal shape and the core drier 30 can be removed from the pin.

Thus, both guide pins in the bottom half of the core box 12 are replaced by the air cylinder operated guide pin plunger 16. As described in detail above, these guide pins are connected to short stroke air cylinders with spring return. When air, or other fluid is supplied to the cylinders, the piston moves down, forcing the rubber bushing 34 to expand in the hole in the drier and partly mushroom out and over the lug pulling and holding the drier tight against the core box. When the roll-over table has cycled over (as in FIGURE 3) the air is exhausted from the cylinder, the spring moves the piston and the rubber bushing contracts, releasing the drier.

While the embodiments of the present invention as herein disclosed constitute preferred forms, it is to be understood that other forms might be adopted.

We claim:

1. A guide pin clamping mechanism for use in a core blowing apparatus; said apparatus including a lower core box half and a core drier adapted to be placed over said lower core box for receiving a core formed in the lower core box portion when said lower core box is inverted, said clamping mechanism attached to said lower core box half; said guide pin clamping mechanism comprised of a pin having a cylindrical shaft portion and a cylindrical head portion of greater diameter, said shaft being disposed perpendicularly to a lug extending from the top surface of said lower core box, said lug having an opening such that said shaft may pass through it, said shaft extending above said core box lug a greater distance than the thickness of a drier lug and terminating at its upper end in said enlarged head portion, said enlarged head portion having a flat lower shoulder and a tapered upper shoulder; a bushing around said shaft of said pin and adapted so as to be firmly affixed in the upper portion of said core box lug,- said bushing extending to or slightly above the upper surface of said lug and having a flat upper radial surface, said bushing having an outer diameter approximating that of said pin head; a cylindrical rubber sleeve around said pin shaft having an inside diameter approximating the diameter of said shaft and located between said upper flat surface of said bushing and said lower flat shoulder of said cylindrical pin head, said rubber sleeve having a fiat upper and lower radial surface and an outside diameter of the approximate size of that of said pin head and said bushing, said rubber sleeve being of a suflicient length to extend from the upper surface of said bushing above the top surface of said core drier lug when said core drier has been located upon the lower core box, said core drier lug having an opening adapted to fit over said pin and said rubber sleeve; and means of pulling said pin such that said pin head compresses said rubber sleeve against said bushing causing said rubber sleeve to expand against the surf-ace of said opening in said core drier lug and to bulge outwardly over the top surface of said core drier lug clamping said core drier to said lower core box.

2. In an automatic core blowing apparatus comprised of a lower core box half, an upper core box half, and a. core drier; a guide pin clamping mechanism situated in said lower core box half, said pin serving as a guide when the upper core box half is lowered over the lower core box half and when the core drier is placed on the lower core box half, said pin also serving to clamp said core drier to said core box half, said guide pin clamping mechanism comprised of a pin with a cylindrical shaft portion and a cylindrical head portion of greater diameter, s-aid shaft being disposed perpendicularly to the lug extending from the top surface of said lower core box half, said lug having an opening such that said shaft may pass through it, said shaft extending above said core box lug a greater distance than the thickness of said core drier lug and terminating at its upper end in said enlarged head portion, said enlarged head portion having a fiat lower shoulder and a tapered upper shoulder; a bushing around said shaft of said pin and adapted so as to be firmly affixed in the upper portion of said core box lug, said bushing extending to or slightly above the upper surface of said lug and having a flat upper radial surface, said bushing having an outer diameter approximating that of said pin head; a cylindrical rubber sleeve around said pin shaft having an inside diameter approximating the diameter of said shaft and located between said upper flat surface of said bushing and said lower flat shoulder of said cylindrical pin head, said rubber sleeve having flat upper and lower radial surfaces and an outside diameter of the approximate size of that of said pin head and said bushing, said rubber sleeve being of sufiicient length to extend from the upper surface of said bushing above the top surface of said core drier lug when said core drier has been located upon the lower core box half, said core drier lug having an opening adapted to fit over said pin and said rubber sleeve; and means of pulling said pin such that said pin head compresses said rubber sleeve against said bushing causing said rubber sleeve to expand against the surface of said opening in said core drier lug and bulge outwardly over the top surface of said core drier lug clamping said core drier to said lower core box half.

3. A guide pin clamping mechanism as claimed in claim 1 wherein said means of pulling said pin comprises a piston, a cylinder, and means of exerting air pressure within said cylinder upon said piston, said piston consisting of a piston rod and piston head, said piston rod being rigidly attached to the end of said pin shaft and disposed such that the axes of said shaft and said piston rod be in a straight line, said piston adapted so as to be reciprocally operable with said cylinder, said cylinder adapted to admit air pressure, said air pressure acting upon said piston head to pull said piston and said pin such that said pin head compresses said rubber sleeve against said bushing causing said rubber sleeve to expand within said core drier lug and bulge outwardly over the top surface of said core drier lug clamping said core drier to said lower core box half.

4. A core molding apparatus comprising, in combination, a lower core box half adapted to mold a core therein with the aid of a upper mold half whereby the molded core is exposed above the upper surface of said lower core box half, a drier adapted to be placed over said lower core box for receiving a core formed in the lower core box portion when said lower core box is inverted, a pin attached to said lower core box half, said pin having an upper cylindrical portion connected to a shaft reciprocally movable relative to said lower core box half, and a lower adjacent elastomeric annular bushing disposed about said shaft and being in a free state of substantially the same diameter as said upper pin portion, and means for moving said shaft downwardly, said drier being adapted to receive the exposed portion of said core and having an opening therein adapted to receive said pin, said elastomeric bushing being capable of being compressed axially and thus expanded radially to a greater diameter than said opening by said upper pin portion when said shaft is moved downward whereby said expanded bushing is operative to lock said drier on said lower core box half.

5. In a core molding apparatus including a lower core box portion, a drier adapted to be placed over said lower core box for receiving a core formed in the lower core box portion when said lower core box is inverted, the improvement comprising of means for temporarily securing said drier to said core box said means comprising a cylindrical pin secured to said lower core box, said drier having an opening therein to receive said pin, said pin having an intermediate elastomeric portion adapted to extend through said opening when said drier is positioned on said core box and means for expanding said elastomeric portion whereby the said elastomeric portion extends beyond the diameter of said opening to thereby lock said drier to said core box.

References Cited by the Examiner UNITED STATES PATENTS 1,027,695 5/1912 Covert 22- 109 X 2,641,033 6/1953 Hines et al. 22110 2,677,160 5/ 1954 Peterson 22-13 2,688,894 9/1954 Modrey 70 3,030,677 4/1962 Kindt et al. 22110 1. SPENCER OVERHOLSER, Primary Examiner. E. MAR, Assistant Examiner, 

5. IN A CORE MOLDING APPARATUS INCLUDING A LOWER CORE BOX PORTION, A DRIER ADAPTED TO BE PLACED OVER SAID LOWER CORE BOX FOR RECEIVING A CORE FORMED IN THE LOWER CORE BOX PORTION WHEN SAID LOWER CORE BOX IS INVERTED, THE IMPROVEMENT COMPRISING OF MEANS FOR TEMPORARILY SECURING SAID DRIER TO SAID CORE BOX SAID MEANS COMPRISING A CYLINDRICAL PIN SECURED TO SAID LOWER CORE BOX, SAID DRIER HAVING AN OPENING THEREIN TO RECEIVE SAID PIN, SAID PIN HAVING AN INTERMEDIATE ELASTOMERIC PORTION ADAPTED TO EXTEND THROUGH SAID OPENING WHEN SAID DRIER IS POSITIONED ON SAID CORE BOX AND MEANS FOR EXPANDING SAID ELASTOMERIC PORTION 